Pathology of the Glomerulus Flashcards
What are podocytes?
They’re in the Bowman’s capsule in the kidneys and wrap around capillaries of the glomerulus - their foot process form the pedicels which aid in barrier to filtration of medium sized proteins
What substances are not filtered at the glomerulus?
All protein equal to or larger than albumin (including immunoglobulin) will NOT be filtered, they will stay in plasma
Describe the filtration barrier of the glomerulus
- Podocytes have interdigitating foot processes around the capillary
- Endothelial cell cytoplasm, basal lamina and podocyte
- Mesangial cells – modified smooth muscle cells and are continuous with vascular smooth muscle of arteriole; control blood flow through glomerulus
What is glomerulonephritis?
Term GN encompasses a number of conditions which:
• Are caused by pathology of glomerulus
• Present with proteinuria, Haematuria or both
• Diagnosed on renal biopsy
• Cause CKD
• Can progress to kidney failure (except minimal change disease)
What is the aetiology of glomerulonephritis?
- Immunoglobulin deposition
* No immunoglobulin deposition i.e. diabetic glomerular disease
What are the common presentations of glomerulonephritis?
- Haematuria (blood in urine)
- Heavy proteinuria (nephrotic syndrome)
- Slowly increasing proteinuria
- Acute renal failure
What are the for main causes of haematuria?
- UTI
- Urinary tract stone
- Urinary tract tumour
• Glomerulonephritis
What investigations are carried out for glomerulonephritis?
- Urine culture
- Ultrasound
- Check clotting then renal biopsy – shows accumulation of mesangial matrix (too many mesangial cells)
- Imummunohistochemistry
What are two immunohistochemistry tests for glomerulonephritis
- Immunoflourescence – immunoglobulin (of IgA type) and complement component C3 in mesangial area of all glomeruli
- Electron microscopy – deposits of IgA with prominent mesangial cells
Describe the pathology of IgA glomerulonephritis
Excess antibody (IgA) presents in serum, as it is stuck in the glomerulus in the mesagium and is not filtered into urine.
IgA stuck in mesagnial cells cause them to proliferate and produce more matrix, causing mesangial cell and matrix expansion
What is the prognosis of IgA nephropathy?
- Usually self-limiting
* Small % go onto chronic renal failure (continues deposition of matrix)
What are the investigations for IgA nephropathy?
Biopsy
• Thickening of glomerular filter
• New basement membrane under glomerular basement
Imunohistochemistry +ve for IgA deposits in matrix
• Basal lamina spike (matrix
What is the presentation of IgA glomerulonephritis?•
- Usually presents as nephritic
- Asymptomatic non-visible haematuria
- Increased BP
- Proteinuria <1g
Describe the pathophysiology of nephrotic syndrome
Filtration barrier is formed by Podocytes, glomerular basement membrane and endothelial cells.
Proteinuria results from podocyte pathology.
What is the presentation of nephrotic syndrome?
Generalised, pitting oedema